Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 250708
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
308 AM EDT Tue Jul 25 2017

.DISCUSSION...

Surface high pressure center positioned over Michigan will move east
today as the upper ridge axis slides in overhead. Deep layer
subsidence and drying will limit cu development, with a field that
forms early in the day under the subsidence inversion thinning out
during the afternoon. Some high clouds will brush the area, however.
Temperatures will warm into the mid 70s to near 80 under good
insolation and dry conditions, with lakeshore areas a little cooler
as the lake breeze works in during the afternoon. Clear skies and
light winds tonight will once again allow favorable radiational
cooling conditions to set up. This will provide another cool night
with mins in the mid 50s to near 60.

The ridge will break down late tonight and Wednesday as the strong
upper wave over Saskatchewan moves across Ontario. This will draw
warmer air into the region on Wednesday and increase mixing,
resulting in what will likely be the warmest day of the week with
highs in the low/mid 80s. It will also drive a surface trough and
cold front down through the northern Great Lakes by late Wednesday
afternoon, with perhaps just the northern counties seeing a chance
for rain/thunder.

The front will only slowly sink southward into central Michigan
Wednesday evening and overnight as the upper trough exits east into
Quebec and it becomes parallel to upper flow. Pacific energy will
meanwhile drop into the northern Mississippi River Valley Wednesday
night, and then across Michigan on Thursday. Small differences with
timing and track of this feature still exist, making convective
forecast for overnight into early Thursday a little bit challenging.
Surface low out ahead of the upper feature is forecast to track
across the corn belt and into the Ohio Valley Wednesday night into
Thursday, with small differences leading to different placement of
the warm front, warm sector, and low-level jet. Best potential for
MCS development looks to stay just to our south and west per
consensus with the 00Z model suite, however a few models (Euro/CMC)
are far enough north with the low track this cycle to bring some
concern for the far southern section of the forecast area to get
clipped by storms early Thursday morning. Otherwise, height falls
and steepening mid-level lapse rates as cooler air arrives aloft
will provide a good chance for showers and thunderstorms along the
front still dropping southward through Michigan at the start of
Wednesday night and through Thursday. Will continue to watch model
solutions to see how these two systems will interact.

High pressure should build back into the area for the end of the
week, bringing a return to quiet weather.

&&

.MARINE...

Northerly flow will diminish below 10 knots this morning and become
basically light and variable this afternoon as high pressure passes
over the area. Southerly winds will return tonight into Wednesday,
topping out around 20 knots as warmer air streams back into the area
between the exiting high pressure and an approaching cold front. This
front may trigger showers and thunderstorms late Wednesday night
into Thursday as it sags south. North to northeast winds will
increase to near 20 knots Thursday night in the wake of this front.
Waves will build in response to this flow, and a Small Craft
Advisory may be needed late Thursday night into Friday for portions
of the nearshore waters.

&&

.HYDROLOGY...

A cold front will progress through the area Thursday morning,
bringing a chance of showers and thunderstorms. Locally heavy
rainfall is not out of the question with rainfall amounts of up to
half an inch possible in some locations. There is some chance of
heavier rain as a convective complex is forecast by pretty much
every model to be in the vicinity. Given recent history, and the
model trends to date, at this time expect this heavier cluster of
storms to brush the area to the south.

&&

.PREV DISCUSSION...
Issued at 1204 AM EDT Tue Jul 25 2017

AVIATION...

A dry and stable environment will exist over the next 24 hours as
high pressure slowly builds into the region.  Clear skies and
light/northeast winds prevail overnight.   A low coverage of cu
possible late Tuesday.  Winds remaining modest from an easterly
direction Tuesday.

//DTW THRESHOLD PROBABILITIES...

* None


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 4 AM EDT early this morning for
     LHZ441>443.

Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

DISCUSSION...HLO
MARINE.......DG
HYDROLOGY....DG
AVIATION.....DG


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.



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